Inductive interconnection system

ABSTRACT

Embodiments describe a receiving element that includes a ferromagnetic structure axially symmetrical around a central axis disposed along a length of the ferromagnetic structure. The ferromagnetic structure includes a groove region defining two end regions on opposing sides of the groove region, where the groove region has a smaller length than the two end regions. The receiving element also includes an inductor coil wound about the groove region of the ferromagnetic structure and in between the two end regions.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 16/127,046, filed on Sep. 10, 2018, which claimspriority to U.S. Provisional Patent Application No. 62/565,460, filed onSep. 29, 2017 and U.S. Provisional Patent Application No. 62/565,471,filed on Sep. 29, 2017, and is related to U.S. Non-Provisional patentapplication Ser. No. 16/127,072, filed on Sep. 10, 2018, the disclosuresof which are herein incorporated by reference in their entirety and forall purposes.

BACKGROUND

Portable electronic devices, such as tablets, smart phones, and thelike, have become ubiquitous in modern day life. The functionality andutility provided by these portable electronic devices enhance the lifeof a user by simplifying tasks, improving productivity, and providingentertainment. Some portable devices, however, are difficult to interactwith because several input methods are simply not provided. Forinstance, the small form factor of some portable electronic devicesresult in devices that do not have a physical keyboard, making typingcumbersome. Additionally, portable electronic devices have a displayscreen which is not a suitable surface on which the user can write witha typical writing utensil, e.g., a pen or pencil.

Accordingly, accessory devices have been developed to complement the useof these portable electronic devices to enhance user experience byfilling in these gaps in usability. For instance, portable keyboardshave been developed to connect with these portable electronic devices toprovide a physical keyboard on which a user can type by pressing keys.Furthermore, electronic writing devices, e.g., styluses, smart pencils,and the like, have been designed to act as a writing utensil for theseportable electronic devices.

In some cases, these accessory devices operate by utilizing power from ahost device, such as the portable electronic device. The power from thehost device can be provided to the accessory devices during use or at anearlier time when the accessory devices are storing power in one or morelocally stored batteries only to be used at a later time. Often, theseaccessory devices couple to the host device through one or more exposedelectrical contacts. Using exposed electrical contacts to charge abattery in an accessory device, however, requires the host device andaccessory device to have exposed electrical contacts. The exposedcontacts can be formed of a plug-and-socket type connection mechanismthat results in one or more openings in both the host and accessorydevices. This can provide an avenue within which dust and moisture canintrude and damage the devices. Furthermore, the plug-and-socket type ofconnections require the host and accessory device to be physicallyconnected together, thereby limiting the ease at which the accessorydevice can be charged by the host device.

SUMMARY

Some embodiments of the disclosure provide an inductive interconnectionsystem that enables wireless power transfer between a host device and anaccessory device. The inductive interconnection system enables theaccessory device to receive power from the host device in variousrotational orientations. This eases the way in which the accessorydevice can receive power from the host device.

In some embodiments, a receiving element includes a ferromagneticstructure having a groove region defining two end regions on opposingsides of the groove region, where each end region includes respectiveinterface surfaces, and the groove region has a smaller length than thetwo end regions. The receiving element can further include an inductorcoil wound about the groove region of the ferromagnetic structure and inbetween the two end regions, where the length of the groove region is adimension that extends along a direction perpendicular to the axis ofthe inductor coil. The receiving element can also include a shieldcomprising a plurality of sidewalls and a back wall that form a cavitywithin which the ferromagnetic structure and inductor coil arepositioned, and a spacer positioned between the ferromagnetic structureand the shield to attach the ferromagnetic structure to the shield.

In some additional embodiments, an inductive interconnection systemincludes a transmitting element and a receiving element. Thetransmitting element includes a transmitting ferromagnetic structurehaving a transmitting groove region defining two transmitting endregions disposed on opposing sides of the transmitting groove region,and a transmitting inductor coil wound about the transmitting grooveregion of the transmitting ferromagnetic structure and in between thetwo transmitting end regions, the transmitting inductor coil configuredto generate time-varying magnetic flux through the transmittingferromagnetic structure. The receiving element can include aferromagnetic structure having a groove region defining two end regionson opposing sides of the groove region, each end region comprisingrespective interface surfaces, wherein the groove region has a smallerlength than the two end regions. The receiving element can furtherinclude an inductor coil wound about the groove region of theferromagnetic structure and in between the two end regions, a shieldcomprising a plurality of sidewalls and a back wall that form a cavitywithin which the ferromagnetic structure and inductor coil arepositioned, and a spacer positioned between the ferromagnetic structureand the shield to attach the ferromagnetic structure to the shield.

In certain embodiments, a stylus for inputting data into a host deviceincludes a housing comprising a curved portion and a flat portion, powerreceiving circuitry disposed within the housing, a receiving elementdisposed within the housing and coupled to the power receivingcircuitry, and an operating system coupled to the power receivingcircuitry and the receiving element, and configured to operate the powerreceiving circuitry and the receiving element to receive power from thehost device. The receiving element includes a ferromagnetic structurehaving a groove region defining two end regions on opposing sides of thegroove region, where each end region includes respective interfacesurfaces, and the groove region has a smaller length than the two endregions. The receiving element can further include an inductor coilwound about the groove region of the ferromagnetic structure and inbetween the two end regions, where the length of the groove region is adimension that extends along a direction perpendicular to the axis ofthe inductor coil. The receiving element can also include a shieldcomprising a plurality of sidewalls and a back wall that form a cavitywithin which the ferromagnetic structure and inductor coil arepositioned, and a spacer positioned between the ferromagnetic structureand the shield to attach the ferromagnetic structure to the shield.

In some embodiments, an alignment device includes a center magnet havingpoles arranged in a vertical orientation, first and second strengtheningmagnets disposed on opposite ends of the center magnet, where the firstand second strengthening magnets having poles arranged in a horizontalorientation, and first and second ferromagnetic structures disposed onouter ends of corresponding first and second strengthening magnets suchthat the first strengthening magnet is disposed between the firstferromagnetic structure and the center magnet, and the secondstrengthening magnet is disposed between the second ferromagneticstructure and the center magnet.

In some additional embodiments, an alignment device including a centerferromagnetic structure; first and second magnets disposed on oppositeends of the center ferromagnetic structure, the first and second magnetshaving polar ends that are arranged in a horizontal orientation, andfirst and second side ferromagnetic structures disposed on ends of thefirst and second magnets such that the first magnet is disposed betweenthe first side ferromagnetic structure and the center ferromagneticstructure, and the second magnet is disposed between the second sideferromagnetic structure and the center ferromagnetic structure.

In certain embodiments, a portable electronic device includes a housing,a battery disposed within the housing, a display disposed within thehousing and configured to perform user interface functions, a processordisposed within the housing and coupled to the display and configured tocommand the display to perform the user interface functions, atransmitting element disposed within the housing, and power transmittingcircuitry coupled to the processor and the battery, wherein the powertransmitting circuitry is configured to route power from the battery tothe transmitting element. The transmitting element includes a centermagnet having poles arranged in a vertical orientation, first and secondstrengthening magnets disposed on opposite ends of the center magnet,the first and second strengthening magnets having poles arranged in ahorizontal orientation, and first and second ferromagnetic structuresdisposed on outer ends of corresponding first and second strengtheningmagnets such that the first strengthening magnet is disposed between thefirst ferromagnetic structure and the center magnet, and the secondstrengthening magnet is disposed between the second ferromagneticstructure and the center magnet.

A better understanding of the nature and advantages of embodiments ofthe present invention may be gained with reference to the followingdetailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary wireless chargingsystem having an inductive interconnection system, according to someembodiments of the present disclosure.

FIGS. 2A-2C illustrate different perspective views of an exemplarytransmitting element, according to some embodiments of the presentdisclosure.

FIG. 3A illustrates a top-down view of an exemplary host device havingtwo transmitting elements, according to some embodiments of the presentdisclosure.

FIG. 3B illustrates a perspective view of a portion of the host deviceshown in FIG. 3A where the transmitting element is incorporated in ahousing and some surfaces of the transmitting element are exposed,according to some embodiments of the present disclosure.

FIG. 3C illustrates a perspective view of a cross-section of theillustration shown in FIG. 3B along the illustrated cut-line, accordingto some embodiments of the present disclosure.

FIG. 4 illustrates an exemplary receiving element configured to receivepower from a transmitting element when it is positioned at any pointalong a limited angular rotation, according to some embodiments of thepresent disclosure.

FIG. 5 illustrates exemplary magnetic interactions between atransmitting element and a receiving element in an inductiveinterconnection system during wireless power transfer, according to someembodiments of the present disclosure.

FIG. 6 is a simplified perspective view diagram of an exemplaryaccessory device, according to some embodiments of the presentdisclosure.

FIG. 7A is a simplified cross-sectional diagram of an accessory deviceat a point across a receiver coil of a receiver element, according tosome embodiments of the present disclosure.

FIG. 7B is a simplified cross-sectional diagram of accessory device at apoint across an interface surface of a receiver element, according tosome embodiments of the present disclosure.

FIG. 8A is a simplified top-down view of an exemplary wireless chargingsystem, according to some embodiments of the present disclosure.

FIG. 8B is a simplified cross-sectional view of an exemplary wirelesscharging system, according to some embodiments of the present disclosure

FIG. 9 is an exploded view diagram of an exemplary receiving assembly,according to some embodiments of the present disclosure.

FIG. 10 is an exploded view diagram of an exemplary transmittingassembly, according to some embodiments of the present disclosure.

FIG. 11A illustrates a perspective view of an inductive interconnectionsystem where a transmitting element is positioned at an angle withrespect to a receiving element, according to some embodiments of thepresent disclosure.

FIG. 11B illustrates a cross-sectional view along the dotted cut linethrough the inductive interconnection system shown in of FIG. 6A,according to some embodiments of the present disclosure.

FIG. 11C is a graph illustrating a degree of power transfer efficiencybetween transmitting and receiving elements with respect to varying bothseparation distance and rotational angle, according to some embodimentsof the present disclosure.

FIG. 12A is a perspective view illustrating an elongated receivingelement, according to some embodiments of the present disclosure.

FIG. 12B illustrates an exemplary inductive interconnection systemincluding an elongated receiving element, according to some embodimentsof the present disclosure.

FIGS. 13A-13C illustrate perspective and plan views of an exemplarytransmitting element capable of receiving power from any position acrossa 360° of angular rotation, according to some embodiments of the presentdisclosure.

FIG. 14A illustrates a perspective view of an inductive interconnectionsystem whose receiving element is moving into position to receive powerfrom a transmitting element, according to some embodiments of thepresent disclosure.

FIG. 14B illustrates an inductive interconnection system when areceiving element is aligned with a transmitting element to receivepower, according to some embodiments of the present disclosure.

FIG. 14C illustrates a cross-sectional view of an inductiveinterconnection system showing exemplary magnetic interactions between atransmitting element and a receiving element during wireless powertransfer, according to some embodiments of the present disclosure.

FIG. 15 is a simplified illustration of an exemplary host alignmentdevice for a host device having a single center magnet, according tosome embodiments of the present disclosure.

FIG. 16 is a simplified illustration of an exemplary host alignmentdevice having a center magnet and two strengthening magnets, accordingto some embodiments of the present disclosure.

FIG. 17A illustrates an exemplary accessory alignment device that can beattracted to a host alignment device at any point along a complete 360°angular rotation, according to some embodiments of the presentdisclosure.

FIG. 17B illustrates an exemplary perspective view of an alignmentsystem including an accessory alignment device and a host alignmentdevice, according to some embodiments of the present disclosure.

FIG. 18 is a graph illustrating a force profile between accessory andhost alignment devices without chamfered edges.

FIG. 19 is a graph illustrating a force profile between accessory andhost alignment device with chamfered edges, according to someembodiments of the present disclosure.

FIG. 20 illustrates an exemplary host device aligned with an exemplaryaccessory device configured to receive charge at any point along acomplete 360° angular rotation, according to some embodiments of thepresent disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosure describe an inductive interconnectionsystem for a wireless charging system that enables wireless powertransfer between a host device and an accessory device. The inductiveinterconnection system can include a transmitting element and areceiving element configured to receive wireless power from thetransmitting element. The transmitting element can be housed within thehost device, and the receiving element can be housed within theaccessory device so that the accessory device can receive power from thehost device. In some embodiments, the transmitting and receivingelements each include a ferromagnetic structure and an inductive coilwound about at least a portion of the ferromagnetic structure. Duringwireless power transfer, the transmitting element can generatetime-varying magnetic flux that can induce a corresponding current inthe receiving element to charge the accessory device. The configurationof the transmitting and receiving elements can enable the accessorydevice to receive power from the host device in various rotationalorientations, as will be discussed in further detail herein.Accordingly, the inductive interconnection system significantly improvesthe ease at which the accessory device can receiver power from the hostdevice.

I. Wireless Charging System

A wireless charging system includes an electronic transmitting devicethat transmits power and an electronic receiving device that receivespower from the electronic transmitting device. According to somedisclosures herein, the electronic transmitting device can be a hostdevice, e.g., a tablet, smart hone, and any other portable consumerelectronic device, that is capable of performing various functions for auser; and, the electronic receiving device can be an accessory device,e.g., a portable keyboard, stylus, smart pencil, wireless earphones, andany other suitable electronic device, that can enhance the function ofthe host device.

FIG. 1 is a block diagram illustrating an exemplary wireless chargingsystem 100 having an inductive interconnection system 105, according tosome embodiments of the present disclosure. Wireless charging system 100include a host device 101 and an accessory device 103 that is configuredto receive power transmitted from host device 101. In some embodiments,host device 101 includes a computing system 102 coupled to a memory bank104. Computing system 102 can execute instructions stored in memory bank104 for performing a plurality of functions for operating device 101.Computing system 102 can be one or more suitable computing devices, suchas microprocessors, computer processing units (CPUs), graphicsprocessing units (GPUs), field programmable gate arrays (FPGAs), and thelike.

Computing system 102 can also be coupled to a user interface system 106,communication system 108, and a sensor system 110 for enabling hostdevice 101 to perform one or more functions. For instance, userinterface system 106 can include a display, speaker, microphone,actuator for enabling haptic feedback, and one or more input devicessuch as a button, switch, capacitive screen for enabling the display tobe touch sensitive, and the like. Communication system 108 can includewireless telecommunication components, Bluetooth components, and/orwireless fidelity (WiFi) components for enabling device 101 to makephone calls, interact with wireless accessories, and access theInternet. Sensor system 110 can include light sensors, accelerometers,gyroscopes, temperature sensors, and any other type of sensor that canmeasure a parameter of an external entity and/or environment.

Host device 101 can also include a battery 112. Battery 112 can be anysuitable energy storage device, such as a lithium ion battery, capableof storing energy and discharging stored energy. The discharged energycan be used to power the electrical components of device 101.

In some embodiments, battery 112 can also be discharged to transmitpower to accessory device 103. For instance, battery 112 can dischargeenergy to power transmitting circuitry 114, which can in turn drive acurrent through transmitting element 116. Driving current throughtransmitting element 116 can cause it to generate time-varying magneticflux 128 that can propagate out of host device 101. Flux 128 caninteract with receiving element 118 and cause a corresponding current tobe generated in receiving element 118. This induced current can then bereceived by power receiving circuitry 120, which can convert thereceived power (e.g., alternating current (AC) power) into usable power(e.g., direct current (DC) power). The usable power can then be providedto battery 122 for storage or to operating system 119 for operatingaccessory device 103.

According to some embodiments of the present disclosure, transmittingelement 116 and receiving element 118 together can be a part of aninductive interconnection system 105. As will be discussed furtherherein, inductive interconnection system 105 can be configured such thataccessory device 103 can receive power from host device 101 when it ispositioned in various rotational orientations. In some embodiments,inductive interconnection system 105 can also include a pair ofalignment devices: a host alignment device 124 and an accessoryalignment device 126. Host alignment device 124 can attract accessoryalignment device 126 so that when they are fully attracted to eachother, transmitting element 116 is aligned with receiving element 118 toensure efficient power transfer between the two elements. Details of theinductive interconnection system 105 will be discussed further herein.

II. Inductive Interconnection System

As mentioned above, an interconnection system for a wireless chargingsystem can include a transmitting element in a host device and areceiving element in an accessory device. The transmitting element canbe configured to generate time-varying magnetic flux that can induce acorresponding current in the receiving element. The current can beconverted to usable power and either stored as energy in the accessorydevice, or immediately used to operate the accessory device. Accordingto some embodiments of the present disclosure, the transmitting andreceiving elements each include a ferromagnetic structure and aninductor coil, as will be discussed further herein.

A. Transmitting Element

FIGS. 2A-2C illustrate different perspective views of an exemplarytransmitting element 200, according to some embodiments of the presentdisclosure. Specifically, FIG. 2A illustrates a perspective view oftransmitting element 200, FIG. 2B illustrates a top-down view oftransmitting element 200, and FIG. 2C illustrates a side-view oftransmitting element 200, according to some embodiments of the presentdisclosure.

With reference to FIG. 2A, transmitting element 200 can include a coil202 and a ferromagnetic structure 204. Coil 202 can be a conductivestrand of wire that is wound about a portion of ferromagnetic structure204. When wound, coil 202 forms an inductor coil that can generatetime-varying magnetic flux when current is driven through coil 202.Ferromagnetic structure 204 can be a structure that can redirect thepropagation of magnetic flux. For instance, ferromagnetic structure 204can be formed of a magnetic material including ferrite, such as MnZn.Because the magnetic properties of ferromagnetic structure 204 canredirect the magnetic flux generated by coil 202 through its body,ferromagnetic structure 204 can be configured to guide the magnetic fluxtoward certain directions based upon its structural design. Forinstance, ferromagnetic structure 204 can include interfacing surfaces206 and 208 that are positioned past a side surface of a groove region212 of ferromagnetic structure 204 to guide the magnetic flux toward acertain direction. A better illustration of the structural configurationof transmitting element 200 is the top-down view shown in FIG. 2B.

As shown in FIG. 2B, transmitting element 200 can include a grooveregion 212 defining two end regions 214 and 216 positioned on opposingsides of groove region 212. Coil 202 can be wound around groove region212 and between (but not around) end regions 214 and 216. As mentionedherein, transmitting element 200 can include two interfacing surfaces206 and 208. Interfacing surfaces 206 and 208 can be respective surfacesof end regions 214 and 216 that are positioned in the same plane. Endregions 214 and 216 can protrude past a surface 210 of groove region 212toward direction D such that the plane in which end regions 214 and 216are positioned is disposed a distance Y_(1,TX) away from a plane inwhich surface 210 resides. As can be noticed in FIG. 2B, surface 210 ishidden behind coil 202 but is represented by a dashed line for clarity.In some embodiments, surface 210 can be connected to interfacingsurfaces 206 and 208 by sidewalls 218 a and 218 b. Thus, sidewalls 218 aand 218 b can be disposed between groove region 212 and end regions 214and 216. Sidewalls 218 a and 218 b can extend a distance Y_(1,TX), whichcan be selected to be any suitable distance equal to or greater than athickness of coil 202. For instance, Y_(1,TX) can be between 0.5 and 1.5mm, such as 1 mm in a particular embodiment. As can be seen in FIG. 2B,the overall structure of transmitting element 200 can have a strongresemblance to the letter “U” of the English alphabet.

In some embodiments, transmitting element 200 can have an overall widthX_(TX) and an overall length Y_(TX). As shown in FIG. 2B, width X_(TX)and length X_(TX) can be a dimension of transmitting element 200 thatextends in a direction that is perpendicular to the axis of coil 202.Additionally, end regions 214 and 216 can have a width X_(1,TX).Dimensions X_(TX), Y_(TX), and X_(1,TX) can be selected to achieve acertain degree of inductive coupling between transmitting element 200and a receiving element, while resulting in an overall size that can fitwithin space constraints of a housing for a host device. In someinstances, widths Xix and X_(1,TX) are selected to be equal to thecorresponding widths of the receiving element for efficient powertransfer. Width X_(TX) can range between 10 mm and 20 mm, width X_(1,TX)can range between 3 mm and 4 mm, and length Y_(TX) can range between 3mm and 4 mm. In some embodiments, groove region 212 can have a length220 that is defined by the difference between length Y_(1,TX) andY_(TX). Thus, length 220 of groove region 212 can be less than lengthY_(TX) in particular embodiments. Accordingly, groove region 212 canhave a smaller length than end regions 214 and 216.

Furthermore, as shown in the side-view perspective of transmittingelement 200 in FIG. 2C, transmitting element 200 can also have a heightZ_(TX). In some embodiments, height Z_(TX) is also selected to achieve acertain degree of inductive coupling between transmitting element 200and a receiving element, while resulting in an overall size that can fitwithin space constraints of a housing for a host device. Z_(TX) canrange between 3 and 4 mm. As can be further seen in FIG. 2C,transmitting element 200 can have a cross-sectional profile that is inthe shape of a rectangle. It is to be appreciated however that therectangular cross-sectional profile of transmitting element 200 in FIG.2C is merely exemplary and that other embodiments can have differentprofile shapes. For instance, some embodiments can have profiles thatare substantially square, circular, ovular, triangular, trapezoidal, andthe like.

It is to be appreciated that end regions 214 and 216 can protrude in anydesired direction. The embodiment illustrated in FIG. 2B shows that endregions 214 and 216 can protrude toward direction D. In someembodiments, direction D is a direction that points toward a receivingelement so that magnetic fields generated by coil 202 are redirectedtoward the receiving element by ferromagnetic structure 204, as will bediscussed further herein with respect to FIG. 5.

FIGS. 3A-3C illustrate a transmitting element incorporated into a hostdevice, according to some embodiments of the present disclosure.Specifically, FIG. 3A illustrates a top-down view of an exemplary hostdevice 300 having two transmitting elements, according to someembodiments of the present disclosure. Host device 300 can be a varietyof different electronic devices including, for example, a tabletcomputer, a smart phone, a laptop computer, among others.

With reference to FIG. 3A, a host device 300 can include a housing 302and one or more transmitting elements disposed within housing 302. Forexample, host device 300 can include two transmitting elements: a firsttransmitting element 304 and a second transmitting element 306. Firstand second transmitting elements 304 and 306 can be positioned proximateto outer surfaces of housing 302 so that they can be positioned as closeas possible to an external device, such as an accessory device thatcontacts an outer surface of housing 302 to wirelessly receive powerfrom host device 300. In some embodiments, first and second transmittingelements 304 and 306 can be located at opposite sides of housing 302.For instance, first transmitting element 304 can be located at a leftside 308 of housing 302, and second transmitting element 306 can belocated at a right side 310 of housing 302. Being positioned at left andright sides 308 and 310 of housing 302 enables host device 300 totransmit power to an accessory device on the left and right sides ofhousing 302.

Although FIG. 3A illustrates host device 300 as having two transmittingelements 304 and 306, embodiments are not limited to suchconfigurations. Additional or alternative embodiments can have more orless than two transmitting elements. For instance, some embodiments canhave four transmitting elements, one located on each of the four sidesof host device 300, or three transmitting elements located on left,right, and top sides of host device 300. Furthermore, FIG. 3Aillustrates two transmitting elements located only at sides of housing302. Embodiments, however, are not so limited. Some embodiments can havea transmitting element positioned proximate to a face of host device 300so that an accessory device can receive power from host device 300 byresting on the face of host device 300.

FIG. 3B illustrates a perspective view of a portion 312 of host device300 shown in FIG. 3A where transmitting element 304 is incorporated inhousing 302 and some surfaces of transmitting element 304 are exposed,according to some embodiments of the present disclosure. As shown,transmitting element 304 is positioned within housing 302 but proximateto an outer surface 314 of housing 302. According to some embodiments ofthe present disclosure, interfacing surfaces 316 and 318 of transmittingelement 304 can face outward, away from outer surface 314, so thatmagnetic flux generated by transmitter coil 320 of transmitting element304 can be directed outward toward a receiving element, as will bediscussed further herein.

To have a better understanding of how transmitting element 304 isincorporated in housing 302, FIG. 3C illustrates a perspective view of across-section of the illustration shown in FIG. 3B along the illustratedcut-line. Transmitting element 304 can be fixed in housing 302 by abracket 322 that is secured to housing 302. Bracket 322 can be anysuitable structure formed of a stiff material, such as stainless steel,and can be secured to housing 302 in any suitable way, such as with anadhesive 324 or a mechanical fastener (not shown). When secured, bracket322 can press transmitting element 304 against housing 302 to fix it inplace with the help of an adhesive material 324. Bracket 322 can includean opening 323 into which transmitter coil 320 can extend to minimizethe amount of space occupied by the entire module. Interfacing surfaces316 and 318 of ferromagnetic structure 326 can face outward and becovered by a radio frequency (RF) window 328. RF window 328 can beformed of a material that is transparent to magnetic flux while alsoproviding a degree of protection against physical damage, such asceramic, sapphire, and the like.

A. Receiving Element

As discussed herein, the structural design of the ferromagneticstructure of a transmitting element enables it to directionally transmitpower to a receiving element by way of its protruded interfacingsurfaces. Similarly, a receiving element can include a ferromagneticstructure that is specifically designed to receive the time-varyingmagnetic flux propagating out of the interfacing surfaces of thetransmitting element when the receiving element is positioned acrossfrom the transmitting element.

In some embodiments, the construction of a receiving element can besubstantially similar to the construction of a transmitting element formwhich it receives wireless power. For instance, FIG. 4 illustrates anexemplary receiving element 400 configured to receive power from atransmitting element when it is positioned directly across from thetransmitting element, according to some embodiments of the presentdisclosure. In certain embodiments, receiving element 400 can besubstantially similar to a transmitting element, like transmittingelement 200 in FIG. 2A. Thus, receiving element 400 can include a coil402 wound about a groove region 410 of ferromagnetic structure 404. Endregions 414 and 416 can be positioned on opposing sides of groove region410 and protrude past a side surface of ferromagnetic structure 404. Endregions 414 and 416 can also include interfacing surfaces 406 and 408through which magnetic flux can enter into and be redirected throughferromagnetic structure 404 to induce a corresponding current in coil402 during wireless power transfer. In some embodiments, coil 402 isformed of approximately 85 turns in a dual-layer configuration, meaningtwo layers of turns: a first layer of turns that winds betweeninterfacing surfaces 406 and 408, and a second layer of turns that windson top of the first layer and between interfacing surfaces 406 and 408.

FIG. 5 illustrates exemplary magnetic interactions between transmittingelement 200 and receiving element 400 in an inductive interconnectionsystem 500 during wireless power transfer, according to some embodimentsof the present disclosure. In this embodiment, transmitting element 200and receiving element 400 are substantially similar in construction, asdiscussed herein with respect to FIG. 4. Furthermore, transmittingelement 200 is shown as being housed within housing 302.

During wireless power transfer, coil 202 can generate a plethora oftime-varying magnetic flux 502 that can propagate in many differentdirections. According to some embodiments of the present disclosure, asubstantial majority of magnetic flux is redirected by ferromagneticstructure 204 so that the flux exits or enters through interfacingsurfaces 208 and 206. As mentioned herein, the shape of ferromagneticstructure 204 can direct the flux toward a certain direction by way ofthe protruding portions, which in this case is toward receiving element400. Accordingly, a concentration of magnetic flux 502 can exist inregions 504 between corresponding interfacing surfaces of ferromagneticstructures 204 and 404.

Depending on the direction of current flowing through coil 202, asubstantial amount of magnetic flux 502 generated by coil 202 can firstflow out of interfacing surface 208 and into interfacing surface 408 offerromagnetic structure 404, which can then propagate throughferromagnetic structure 404 and exit out of interfacing surface 406 sothat magnetic flux 502 can enter back into ferromagnetic structure 204through interfacing surface 206. The resulting flow magnetic flux formsa magnetic loop 506 that induces a current in coil 402 that can be usedto provide power to an accessory device within which receiving element400 is disposed. It is to be appreciated that although magnetic loop 506is shown in a clockwise direction, magnetic loop 506 can also propagatein a counter-clockwise direction when current is flowing through coil202 in an opposite direction.

Although FIG. 5 illustrates transmitting element 200 as transmittingpower to receiving element 400, embodiments are not so limited. Otherembodiments can reverse the transfer of power such that transmittingelement 200 receives power from receiving element 400. As an example,current can be driven into coil 402 of receiving element 400 such thatcoil 402 generates time-varying magnetic flux. The generatedtime-varying magnetic flux can be redirected by ferromagnetic structure404, which can be received by ferromagnetic structure 204. The receivedmagnetic flux in ferromagnetic structure 204 can induce a correspondingcurrent in coil 202, which can be used to provide power to a host devicewithin which transmitting element 200 is disposed.

As can be understood in FIG. 5, the orientation of receiving element 400with respect to transmitting element 200 can substantially affect theefficiency at which power is transferred in inductive interconnectionsystem 500. In some embodiments, optimal power transfer is achieved whentransmitting element 200 is aligned with receiving element 400, and whenthe two elements are oriented such that interfacing surfaces 406 and 408of ferromagnetic structure 404 are facing toward correspondinginterfacing surfaces 206 and 208 of ferromagnetic structure 204.Furthermore, optimal power transfer can be achieved when the separationdistance 426 between transmitting and receiving elements 200 and 400 isminimized.

According to some embodiments of the present disclosure, receivingelement 400 can be incorporated within an accessory device to enablewireless power transfer between a host device, e.g., host device 300 inFIG. 3, and the accessory device. FIG. 6 is a simplified perspectiveview diagram of an exemplary accessory device 600, according to someembodiments of the present disclosure. As shown in FIG. 6, accessorydevice 600 can be any suitable electronic device having an operatingsystem, power receiving circuitry, and a battery, such as accessorydevice 103 in FIG. 1. Accessory device 600 can be operated to input datainto a host device. As an example, accessory device 600 can be a stylusor a smart pencil that a user can use to make contact with the hostdevice to input data into the host device. Accordingly, in someembodiments, accessory device 600 can include a housing 602 having aback end 606 and an interfacing end 604 opposite of back end 606 that isconfigured to make contact with the host device. For instance,interfacing end 604 can have a structure that tapers to a tip to mimicthe tip of a conventional writing utensil, such as a pencil or pen.

In some embodiments, housing 602 of accessory device 600 can include acurved surface portion 608 and a flat portion 610 that both extendbetween at least a portion of interfacing end 604 and back end 606 ofhousing 602. Flat portion 610 can include a receiving surface 611,against which a housing for a host device can be positioned toeffectuate wireless power transfer, as will be discussed herein withrespect to FIGS. 7A-7B and 8A. According to some embodiments, accessorydevice 600 can include a receiving element 612 disposed within andadjacent to flat portion 610 of housing 602. Receiving element 612 canhave the same form and function as receiving element 400 discussedherein with respect to FIGS. 4 and 5. Thus, receiving element 612 caninclude a ferromagnetic structure 605 having interfacing surfaces 614and 616, and a receiver coil 618 wound about a groove region (not shown,but similar to groove region 410 of receiving element 400 in FIG. 4) offerromagnetic structure 605. In some embodiments, interfacing surfaces614 and 616 can face toward flat portion 610 of housing 602 so thataccessory device 600 can wirelessly receive power by interacting withmagnetic flux propagating from a transmitting element through flatportion 610. The cross sectional profile of housing 602 can resemble anupper case letter “D”, as better illustrated in FIGS. 7A and 7B.

FIGS. 7A and 7B illustrate cross-sectional views of accessory device 600at different locations, according to some embodiments of the presentdisclosure. Specifically, FIG. 7A is a simplified cross-sectionaldiagram 700 of accessory device 600 at a point across receiver coil 618of receiving element 612, and FIG. 7B is a simplified cross-sectionaldiagram of accessory device 600 at a point across interface surface 616of receiving element 612, according to some embodiments of the presentdisclosure.

As shown in FIG. 7A, housing 602 includes curved portion 608 and flatportion 610 that extend along a length (i.e., parallel to the centeraxis) of housing 602. Curved and flat portions 608 and 610 can form amonolithic structure that can enclose one or more electrical componentswithin it, such as receiving element 612, as discussed herein withrespect to FIG. 6. In addition to receiving element 612, housing 602 canalso enclose various other components such as, but not limited to, ashield 702, a support frame 704, one or more electrical components 715,and a driver board 717 upon which component 715 is mounted. Shield 702can be formed of any material suitable for blocking magnetic fluxpropagating around receiving element 612 from being exposed onelectrical component(s) 715 within housing opening 710 of housing 602.For instance, shield 702 can be formed of copper. Electricalcomponent(s) 715 can be any suitable electronic device for operatingaccessory device 600 and/or receiver coil 618. For instance, electricalcomponent(s) 715 can be a microcontroller, field programmable logicarray (FPGA), application specific integrated circuit (ASIC), and thelike. Electrical component(s) 715 can be electrically coupled toreceiver coil 618 of receiving element 612 to receive wireless power,such as by receiving current from receiver coil 618 induced by amagnetic flux generated by a transmitter element.

In some embodiments, shield 702 is constructed and positioned in a waythat enhances the blockage of magnetic flux. For instance, shield 702can include an inner bottom surface 714 and inner side surfaces 716 and718 that form a cavity within which receiving element 612 is disposed sothat shield 702 is positioned around five sides of receiving element612. A perspective view of shield 702 is shown in FIG. 9, which will bediscussed further herein. By being positioned around five sides ofreceiving element 612, shield 702 can enhance its ability to blockmagnetic flux from propagating into opening 710 and/or outside ofaccessory device 600. In some embodiments, shield 702 can include outerside surfaces 720 and 722 and outer back surface 724. Outer sidessurfaces 720 and 722 can conform to the profile of support frame 704 andthus have a curved profile, while outer back surface 724 can besubstantially flat to provide space, e.g., housing opening 710, withinwhich components, e.g., electrical component(s) 715, of accessory device600 can be positioned. In some embodiments, the thickness of shield 702is greater for regions between inner side surfaces 716 and 718 andrespective outer side surfaces 720 and 722, as shown in FIG. 7A. Thethicker parts of shield 702 can provide a more structurally robustshielding component, as well as provide additional structural protectionfor receiving element 612. In particular embodiments, outer back surface724 is positioned along a center vertical line 712 that divides theaccessory device into two halves. In such embodiments, shield 702 ispositioned within regions of one half of the accessory device.

Support frame 704 can be any suitable structure capable of providingstructural support for housing 602 and protection for the internalcomponents of accessory device 600 from mechanical stress. In certainembodiments, support frame 704 is positioned against an inner surface ofhousing 602 and extends along an area of the inner surface except forregions between receiving element 612 and flat portion 610 of housing602, as shown in FIG. 7A. Support frame 704 can be formed of anysuitable stiff material, such as aluminum, steel, and the like.

In some embodiments, a gap 706 can exist between receiving element 612and inner side surfaces 716 and 718 and bottom surface 714 of shield702. Gap 706 can be vacant space that helps to electrically isolatereceiver coil 618 from shield 702 to ensure optimal operating efficiencyof receiver coil 618. If gap 706 is too small, receiver coil 618 may betoo close to shield 702, thereby decreasing the efficiency at whichreceiver coil 618 can operate. In some embodiments, gap 706 is between0.2 and 0.4 mm, particularly 0.3 mm in certain embodiments. Receivingelement 612 can be physically coupled to shield 702 to minimizesusceptibility to mechanical strain. For instance, receiving element 612can be coupled to shield 702 by one or more spacers 726, as shown inFIG. 7B. Spacers 726 can be directly attached to ferromagnetic structure605 of receiving element 612 and inner bottom surface 714 and at least aportion of both inner side surfaces 716 and 718 of shield 702. In someembodiments, spacers 726 are positioned against surfaces offerromagnetic structure 605 opposite of interface surfaces 614 and 616.Thus, spacers 726 can be positioned on opposite sides of receiver coil618. Any suitable adhesive, such as pressure sensitive adhesive (PSA),can be used to attach spacer 726 between ferromagnetic structure 605 andshield 702. Utilizing spacers 726 can fix receiving element 612 in spaceto prevent it from shifting around during use. In some embodiments,spacer 726 is designed to have a thickness suitable for positioningreceiving element 612 a certain distance away from shield 702 to ensureelectrical isolation of receiver coil 618 and shield 702. For example,spacer 726 can have a thickness between 0.5 and 0.7 mm, particularlyapproximately 0.6 mm in some instances.

It is to be appreciated that even though FIGS. 6 and 7A-7B illustrate anaccessory device as having a housing that includes only one flat region,embodiments are not so limited. Other embodiments can have more flatregions around housing, such as two, three, or even six. Furthermore, anaccessory device may not have any curved regions in its housing.Instead, the housing can be formed of a plurality of flat regions sothat the cross-sectional profile is in a geometrical shape, such as atriangle, square, rectangle, pentagon, hexagon, and the like. It is tobe appreciated that any suitable cross sectional profile can be usedwithout departing from the spirit and scope of the present disclosure.

During the operation of a wireless charging system, as discussed hereinwith respect to FIG. 5, a transmitting element can be positioned near areceiving element to effectuate wireless power transfer by generatingmagnetic flux, which can interact with the receiving element to induce acurrent in the receiving element to charge a battery of an accessorydevice. An example of a wireless charging system including accessorydevice 600 is shown in FIGS. 8A-8B.

FIG. 8A is a simplified top-down view of an exemplary wireless chargingsystem 800, according to some embodiments of the present disclosure;and, FIG. 8B is a simplified cross-sectional view of exemplary wirelesscharging system 800, according to some embodiments of the presentdisclosure. System 800 includes an accessory device, e.g., accessorydevice 600, as discussed herein with respect to FIGS. 6 and 7A-7B, and ahost device, e.g., host device 300 discussed herein with respect toFIGS. 3A-3C, to which accessory device 600 is coupled to receive powerwirelessly. For brevity, reference numerals used in FIGS. 3A-3C, 6, and7A-7B are used in FIG. 8 to indicate their correlation, and thus detailsof such components can be referenced in the respective figures.Furthermore, for clarity and ease of understanding, housing 602 andshield 702 of accessory device 600 are drawn with dotted lines whilehousing 302 of host device 300 is drawn with solid lines, and portionsof respective housings are transparent so the internal components of thedevices can be seen.

As shown, accessory device 600 is positioned against host device 300 toallow wireless power transfer. When positioned, receiving surface 611 ofaccessory device 600 can be in contact, or in close proximity to, outersurface 314 of host device 300; and, both receiving element 612 andtransmitting element 304 can be positioned so that interface surfaces614 and 616 of receiving element 612 face toward interface surfaces 316and 318 of transmitting element 304 to concentrate the propagation ofmagnetic flux between them, which is discussed herein with respect towireless charging system 500 in FIG. 5. That way, magnetic fluxgenerated by transmitter coil 320 can be redirected by ferromagneticstructure 326 toward ferromagnetic structure 605, and then induce acorresponding current in receiver coil 618 by propagating throughferromagnetic structure 605.

During wireless power transfer, shield 702 can prevent stray flux fromexposing onto other internal components within accessory device 600 orfrom exiting out of housing 602. Similarly, host device 300 can alsoinclude a shield 802 to prevent stray flux from exposing onto otherinternal components within host device 300 or from exiting out ofhousing 302. Shield 802 can be a sheet of copper, or any other suitablematerial for blocking magnetic flux, that extends behind transmittingelement 304, e.g., on a side of transmitting element 304 opposite of theside where transparent window 328 is positioned. In some embodiments,shield 802 can extend beyond the farthest left and right edges oftransmitting element 304 to enhance the shielding capabilities of shield802.

In some embodiments, flat portion 610 of housing 602 can be transparentto magnetic flux such that magnetic flux can freely pass through itsstructure, while also providing a degree of protection against physicaldamage. For instance, flat portion 610 can be formed of a material suchas ceramic, sapphire, and the like. In some embodiments, the entire flatportion 610 can be transparent to magnetic flux, or only a part of theflat portion 610 that is disposed along the path of magnetic fluxpropagation, such as parts of flat portion 610 that are coveringinterface surfaces 614 and 616 or parts of flat portion 610 that arepositioned directly across from RF window 328, can be transparent tomagnetic flux. That way, magnetic flux generated by transmitting element304 can freely travel through RF window 328 and flat portion 610 ofhousing 602 to be received by receiving element 612 to effectuatewireless power transfer.

In some embodiments, the relative dimensions of transmitting element 304and receiving element 612 can be adjusted to improve alignmenttolerances so that accessory device 600 can still receive power fromhost device 300 when accessory device 600 is not exactly aligned withhost device 300, e.g., when the respective horizontal axes oftransmitting element 304 and receiving element 612 do not overlap withone another. For instance, as shown in FIG. 8B, height Z_(TX) oftransmitting element 304 can be shorter than a height Z_(RX) ofreceiving element 612. By having a greater height Z_(RX), receivingelement 612 can shift a few millimeters upward or downward and still besuitably positioned to receive power from transmitting element 304without suffering a significant decrease in power transfer efficiency.

FIGS. 9 and 10 are exploded view diagrams of receiving and transmittingassemblies 900 and 1000 to better illustrate the different componentsthat form the receiving and transmitting elements. Specifically, FIG. 9is an exploded view diagram of receiving assembly 900 includingreceiving element 612, and FIG. 10 is an exploded view diagram of anexemplary transmitting assembly 1000 including transmitting element 304.

As shown in FIG. 9, receiving assembly 900 can include receiving element612, shield 702, and spacer 726. Receiving element 612 can includeferromagnetic structure 605 and receiver coil 618 as discussed hereinwith respect to FIG. 6. These components are also discussed in moredetail with respect to corresponding components 404 and 402 in FIG. 4.Shield 702 can block magnetic flux from propagating to other internalcomponents of accessory device 600 as well as block magnetic flux fromexiting accessory device 600, and spacer 726 can fix receiving element612 in position and prevent receiver coil 618 from being too close toshield 702, as discussed herein with respect to FIG. 7B. Shield 702 canbe a five-sided box formed of four sidewalls and a back wall that formsa cavity 910 within which receiving element 612 and spacer 726 can bedisposed. When disposed in cavity 910, interface surfaces 614 and 616 ofreceiving element 612 can face toward outside of cavity 910. In someinstances, shield 702 can include two extensions 912 and 914 to providemore surface area with which to attach to an anchor point within housing602 of accessory device 600. Extensions 912 and 914 can extend fromrespective sidewalls of shield 702 in a direction parallel to a plane inwhich the back wall is oriented. Extensions 912 and 914 can be securedto an anchor point to prevent shield 702 from shifting and becomingloose. In addition, shield 702 can also include an opening 916 near theback side of shield 702. Opening 916 can provide a passage way throughwhich wires can thread. For example, wire 918 that forms receiver coil618 can enter and exit cavity 910 of shield 702 through opening 916.That way, wire 918 can make electrical connection with a driver board(not shown) or any other driving component configured to operatereceiver coil 618 during wireless power transfer.

In some embodiments, spacer 726 can be formed of two separate parts: afirst part 902 and a second part 904. Each part 902 and 904 can beattached to and positioned behind a respective portion of ferromagneticstructure 605. For instance, first part 902 can be positioned behindinterface surface 614 and second part 904 can be positioned behindinterface surface 616. Spacer 726 is made up of two parts so thatreceiver coil 618 can be positioned between first and second parts 902and 904 of spacer 726. In some embodiments, each part 902 and 904 caninclude a retainer that overlaps parts of ferromagnetic structure 605.As an example, first part 902 can include individual retainers 906 a-ccoupled to a back retainer 907 and second part 904 can includeindividual retainers 908 a-c coupled to a back retainer 909. Individualretainers 906 a-c and back retainer 907 can form a monolithic structure,and the same can be said for retainers 908 a-c and back retainer 909.Each retainer can overlap respective portions of top, bottom, and sidesurfaces of ferromagnetic structure 605 to increase the amount ofsurface area parts 902 and 904 are in contact with ferromagneticstructure 605. This increase in surface area creates a stronger couplingbetween spacer 726 and ferromagnetic structure 605 so that spacer 726can better fix receiving element 612 in place and prevent it fromdetaching and becoming loose when experiencing drop events. AlthoughFIG. 9 illustrates retainers 906 a-c and 908 a-c as individual, separateextensions of respective back retainers 908 and 908, embodiments are notlimited to such embodiments. In some instances, instead of havingmultiple individual retainers, each part 902 and 904 can have a singleretainer that wraps around three consecutive sides of ferromagneticstructure 605 in an uninterrupted manner.

With reference to FIG. 10, transmitting assembly 1000 can includetransmitting element 304, spacer 1002, and a stiffener 1004.Transmitting element 304 can include ferromagnetic structure 326 andtransmitter coil 320 as discussed herein with respect to FIGS. 3A-3C.These components are also discussed in more detail with respect tocorresponding components 204 and 202 in FIGS. 2A-2C. Stiffener 1004 canbe a hard component that provides structural support for transmittingelement 304 and provide a structure upon which transmitting element 304can be mounted. In some embodiments, stiffener 1004 is a plate that isformed of a stiff material, such as, but not limited to, FR4. Spacer1002 can be formed of two parts: a first part 1006 and a second part1008, that can be positioned on either end of transmitter coil 320.Spacer 1002 can couple ferromagnetic structure 326 to stiffener 1004 sothat transmitting element 304 is substantially fixed in place. In someembodiments, transmitting element 304 is attached to stiffener 1004 sothat interface surfaces 316 and 318 are facing in a direction that isperpendicular to the direction in which stiffener 1004 is facing. Thatway, interface surfaces 316 and 318 can be positioned to direct magneticflux to a receiving element, as shown and discussed herein with respectto FIGS. 3B-3C and 5. Wire 1010 that is used to form transmitter coil320 can be coupled to a connector 1007 containing contact pads 1008 a-b.Each termination end of transmitter coil 320 can make contact with arespective contact pad so that wire 1010 can make electrical connectionwith a driver board (not shown) or any other driving componentconfigured to operate transmitter coil 320 during wireless powertransfer.

Although the wireless charging systems discussed herein with respect toFIGS. 5 and 8A have the transmitting and receiving elements positionedso that the respective interface surfaces are directly facing oneanother for wireless power transfer, embodiments are not limited to suchalignment constraints. Rather, some embodiments herein enable wirelesscharging even though transmitting and receiving elements are notdirectly facing one another. For instance, the receiving element can bespecifically designed to receive the time-varying magnetic fluxpropagating out of the interfacing surfaces in various rotatableorientations. As an example, the receiving element can have a designthat enables power transfer at any point along a limited angularrotation and another design that enables power transfer at any pointalong a complete 360° angular rotation, as will be discussed furtherherein.

1. Receiving Element Enabling Limited Angular Rotation

The transmitting element in a host device can transmit power to areceiving element by way of the interfacing surfaces of itsferromagnetic structure. According to some embodiments of the presentdisclosure, the receiving element can be specifically designed toreceive the time-varying magnetic flux propagating out of theinterfacing surfaces so that the receiving element can still receivepower from the transmitting element when it is positioned at any pointalong a limited angular rotation.

According to some embodiments of the present disclosure, theconcentration of magnetic flux between interfacing surfaces oftransmitting and receiving elements 200 and 400 (discussed herein withrespect to FIGS. 2A-2C and 4) enables sufficient power transfer evenwhen separation distance 426 is increased due to an adjustment of anangular orientation of transmitting element 200 with respect toreceiving element 400. FIG. 11A illustrates a perspective view of aninductive interconnection system 1100 where a transmitting element 1102is positioned at an angle with respect to a receiving element 1104,according to some embodiments of the present disclosure. Transmittingand receiving elements 1102 are similar in function and construction astransmitting and receiving elements 200 and 400 discussed herein withrespect to FIGS. 2A-2C and 4. Thus, detailed descriptions of suchelements can be referenced in those figures and are not discussed herefor brevity.

As shown, transmitting element 1102 is disposed within housing 1108 of ahost device and is positioned proximate to receiving element 1104 thatis disposed within housing 1106 of an accessory device. In someinstances, housing 1108 can be rotated a certain degree such thathousing 1108 is tilted with respect to housing 1106 as shown in FIG.11B. This can occur, for example, when the host device is a tablet andthe accessory device is a keyboard accessory and that the tablet istilted so that the screen is angled upward toward a user's face.

FIG. 11B illustrates a cross-sectional view along the dotted cut linethrough inductive interconnection system 1100 shown in of FIG. 11A,according to some embodiments of the present disclosure. When housing1108 is rotated at an angle 1109 with respect to housing 1106 aroundpivot point 1112, respective transmitting and receiving elements 1102and 1104 are correspondingly rotated along angle 1109. Accordingly,transmitting element 1102 can be disposed a rotational separationdistance 1110 away from receiving element 1104. The rotation causes agreater net separation between transmitting and receiving element 1102and 1104 than if no rotation is present. Thus, in some instances,rotational separation distance 1110 can be greater than separationdistance 508 discussed herein with respect to FIG. 5 even though thedistance between the very bottom corner of transmitting element 1102 andreceiving element 1104 may be substantially the same as distance 508.The degree of inductive coupling between transmitting and receivingelements can thus depend on at least two factors: separation distanceand rotational angle, as shown in FIG. 11C.

FIG. 11C is a graph 1101 illustrating a degree of power transferefficiency between transmitting and receiving elements with respect tovarying both separation distance and rotational angle. Graph 1101 has ay-axis representing a degree of power transfer efficiency in percentagesincreasing upwards, and an x-axis representing a degree of separationdistance in millimeters increasing to the right. Three plots are shownin graph 1101, each representing a different degree of angular rotation:plot 1120 representing a 0° angular rotation, plot 1122 representing a20° angular rotation, and plot 1124 representing a 45° angular rotation.

As shown in graph 1101, percentage of power transfer efficiencydecreases as separation distance increases. Graph 1101 further showsthat as angular rotation increases, power transfer efficiency decreasesfurther across all separation distances. Thus, the losses of inductivecoupling caused by angular rotation adds to the losses of inductivecoupling caused by separation distance. However, it is to be appreciatedthat embodiments herein can still enable sufficient power transfer evenwith a degree of angular rotation. For instance, if the power transferefficiency threshold for sufficient wireless power transfer between atransmitting element and a receiving element is 20% power transferefficiency, then successful power transfer can still be achieved by aninductive interconnection system whose separation distance is less than5.5 mm and whose angular rotation is less than 45°. These limits howeverare merely exemplary and that they can change depending on desired powertransfer efficiency.

Disclosures aforementioned herein discuss angular rotation around asingle pivot point, e.g., pivot point 1112 in FIG. 11B; however,embodiments are not limited to configurations that can only pivot roundone pivot point. Some embodiments can pivot across any point along anelongated receiving element, as discussed herein with respect to FIGS.12A and 12B.

FIG. 12A is a perspective view illustrating an elongated receivingelement 1200, according to some embodiments of the present disclosure.In some embodiments, elongated receiving element 1200 can havesubstantial similarities to transmitting element 200 discussed hereinwith respect to FIG. 2A. For example, elongated receiving element 1200can include a ferromagnetic structure 1204 and a coil 1202 wound about acentral portion 1212 of ferromagnetic structure 1204. Ferromagneticstructure can also include end regions 1214 and 1216 that protrude pasta side surface (not shown, but positioned similarly to surface 210 inFIG. 2A) and have interfacing surfaces 1206 and 1208. Thus, whenelongated receiving element 1200 is observed from direction 1220, theobserved structure is substantially similar to receiving element 400 inFIG. 4, which is substantially similar to transmitting element 200 ofFIG. 2A. However, elongated receiving element 1200 can include asubstantially greater height 1218 than height Z_(TX) of transmittingelement 200 in FIG. 2A. In some embodiments, height 1218 is greater thanthe widths of central portion 1212 and end regions 1214 and 1216combined. The greater height allows a receiving element to receive powerfrom any point along height 1218, thereby providing a larger area atwhich receiving element can be positioned to receive charge.

For instance, FIG. 12B illustrates an exemplary inductiveinterconnection system 1201 including elongated receiving element 1200,according to some embodiments of the present disclosure. Elongatedreceiving element 1200 can wirelessly receive a sufficient amount ofpower from transmitting element 1222 when transmitting element 1222 ispositioned along any point across height 1218. As an example, elongatedreceiving element 1200 can receive power from transmitting element 1222when it is positioned at any one of points 1224, 1226, and 1228.

2. Receiving Element Enabling 360° Rotation

As discussed with respect to the aforementioned figures, a receivingelement can be configured to receive power from a transmitting elementin a limited range of angular rotation. However, as will be discussedfurther herein with the following figures, a receiving element can beconfigured to receive power from a transmitting element at any pointalong a complete 360° range of angular rotation, according to someembodiments of the present disclosure. Accordingly, an accessory devicewithin which the receiving element is disposed can receive power from ahost device regardless of how the receiving element is rotated along itsaxis. This enables the accessory device to be easily placed against thehost device to receive power, thereby substantially enhancing userexperience.

FIGS. 13A-13C illustrate perspective and plan views of an exemplaryreceiving element 1300 capable of receiving power from any positionacross a 360° of angular rotation, according to some embodiments of thepresent disclosure. Specifically, FIG. 13A illustrates a perspectiveview of receiving element 1300, FIG. 13B illustrates a top-down view ofreceiving element 1300, and FIG. 13C illustrates a side-view ofreceiving element 1300, according to some embodiments of the presentdisclosure.

With reference to FIG. 13A, receiving element 1300 can include a coil1302 and a ferromagnetic structure 1304. Coil 1302 can be a conductivestrand of wire that is wound about a portion of ferromagnetic structure1304. When wound, coil 1302 forms an inductor coil that can generatetime-vary magnetic flux when current is driven through coil 1302.Ferromagnetic structure 1304 can be a structure that can redirect thepropagation of magnetic flux. For instance, ferromagnetic structure 1304can be formed of a magnetic material including ferrite, such as MnZn.

Because the magnetic properties of ferromagnetic structure 1304 canredirect the magnetic flux generated by coil 1302 through its body,ferromagnetic structure 1304 can be configured to guide the magneticflux toward all directions in a 360° manner based upon its structuraldesign. For instance, unlike the rectangular block-like structure ofreceiving element 400 in FIG. 4A, receiving element 1300 can besubstantially cylindrical in form. In some embodiments, receivingelement 1300 can be symmetrical about a central axis 209 disposed alonga length of ferromagnetic structure 1304. A channel 1311 can bepositioned along central axis 209 and provide vacant space through whichobjects, such as wires, cables, and the like, can tunnel. Receivingelement 1300 can include interfacing surfaces 1306 and 1308 that arepositioned past an outer surface of a groove region of ferromagneticstructure 1304. A better illustration of the structural configuration ofreceiving element 1300 is shown in the top-down view of FIG. 13B.

As shown in FIG. 13B, receiving element 1300 can include a groove region1312 defining two end regions 1314 and 1316 positioned on opposing sidesof groove region 1312. Coil 1302 can be wound around groove region 1312and between (but not around) end regions 1314 and 1316. As mentionedherein, receiving element 1300 can include two interfacing surfaces 1306and 1308, which can be respective surfaces of end regions 1314 and 1316that are positioned the same distance away from central axis 1309.Interfacing surfaces 1306 and 1308 can be axially symmetrical aroundcentral axis 1309 so that it is substantially annular in shape. Endregions 1314 and 1316 can protrude past a surface 1310 of groove region1312 such that interfacing surfaces 1306 and 1308 are disposed adistance Y_(1,RX) away from surface 1310. As can be noticed in FIG. 13B,surface 1310 is hidden behind coil 1302 but is represented by a dashedline for clarity. In some embodiments, surface 1310 can be connected tointerfacing surfaces 1306 and 1308 by sidewalls 1318 a and 1318 b. Thus,sidewalls 1318 a and 1318 b can be disposed between groove region 1312and end regions 1314 and 1316. Sidewalls 1318 a and 1318 b can extend adistance Y_(1,RX), which can be selected to be any suitable distancegreater than or equal to a thickness of coil 1302. For instance,Y_(1,RX) can be between 0.5 and 1.5 mm, such as 1 mm in a particularembodiment. In some embodiments, end regions 1314 and 1316 can be in theshape of flanges that flare outward from central axis 1309. As can beseen in FIG. 13B, the overall structure of receiving element 1300 canhave a strong resemblance to the structure of a bobbin.

In some embodiments, receiving element 1300 can have an overall widthX_(RX) and an overall diameter d_(RX). Additionally, end regions 1314and 1316 can have a width X_(1,RX). Dimensions X_(RX), Y_(RX), andX_(1,RX) can be selected according to design. For instance, dimensionsX_(Rx), Y_(Rx), and X_(1,RX) can be selected to achieve a certain degreeof inductive coupling between receiving element 1300 and a transmittingelement, while resulting in an overall size that can fit within spaceconstraints of a housing for an accessory device. In some instances,widths X_(Rx) and X_(1,RX) are selected to be equal to the correspondingwidths of the transmitting element for efficient power transfer. WidthX_(Rx) can range between 10 mm and 80 mm, width X_(1,RX) can rangebetween 3 mm and 4 mm, and length Y_(RX) can range between 3 mm and 4mm.

Furthermore, as shown in the side-view perspective of receiving element1300 in FIG. 13C, receiving element 1300 can also have a length d_(Rx)and a radial thickness y_(Rx). Length d_(Rx) can also be defined as thediameter of receiving element 1300. In some embodiments, length d_(Rx)and radial thickness y_(RX) are also selected to achieve a certaindegree of inductive coupling between receiving element 1300 and areceiving element, while resulting in an overall size that can fitwithin space constraints of a housing for an accessory device. Inparticular embodiments, d_(Rx) can range between 7 and 8 mm, and radialthickness y_(RX) can range between 3 and 4 mm. In some embodiments,radial thickness y_(RX) can be equal to the overall length Y_(TX) of thetransmitter coil from which it receives power, an example of which canbe referenced in FIG. 2A. In some further embodiments, groove region1312 in FIG. 13B can have a length 1320 that is defined by thedifference between length Y_(1,RX) and d_(RX). Thus, length 1320 ofgroove region 1312 can be less than length d_(RX) in particularembodiments. Accordingly, groove region 1312 can have a smaller lengththan end regions 1316 and 1316.

It is to be appreciated that end regions 1314 and 1316 can protrude awayfrom, and in an orientation perpendicular to, central axis 1309, andaround the entire circumference of receiving element 1300. Thus, endregions 1314 and 1316 can protrude continuously around central axis1309. According to embodiments of the present disclosure, this enablesreceiving element 1300 to receive power from a transmitting element inany rotational orientation around central axis 1309, as will bediscussed further herein with respect to FIGS. 14A-14C.

FIG. 14A illustrates a perspective view of an inductive interconnectionsystem 1400 whose receiving element 1300 is moving into position toreceive power from transmitting element 200, according to someembodiments of the present disclosure. As mentioned herein with respectto FIG. 2A, transmitting element 200 can include coil 202 wound about acentral portion of ferromagnetic structure 204, which has interfacingsurfaces 206 and 208. To receive power, receiving element 1300 can bemoved toward and into alignment with transmitting element 200 such thatinterfacing surfaces 1306 and 1308 of receiving element 1300 arepositioned proximate to respective interfacing surfaces 206 and 208 oftransmitting element 200.

FIG. 14B illustrates inductive interconnection system 1400 whenreceiving element 1300 is aligned with transmitting element 200 toreceive power, according to some embodiments of the present disclosure.Transmitting element 200 is shown as being housed within housing 302, asdiscussed herein with respect to FIG. 3, which can be a housing for anysuitable portable electronic device (e.g., a tablet computer, a smartphone, a laptop computer, and the like). When aligned, coil 202 cangenerate time-varying magnetic flux that can induce a correspondingcurrent in coil 1302 regardless of how receiving element 1300 is rotatedalong rotational pathway 1401 around central axis 1309. This is becausereceiving element 1300 is axially symmetrical around central axis 1309so that no matter how receiving element 1300 is rotated around centralaxis 1309, the electrical interactions between it and transmittingelement 200 are not impacted and can continue to transfer power. Abetter illustration of this concept is shown in FIG. 14C.

FIG. 14C illustrates a cross-sectional view of inductive interconnectionsystem 1400 showing exemplary magnetic interactions between transmittingelement 200 and receiving element 1300 during wireless power transfer,according to some embodiments of the present disclosure. Transmittingelement 200 is shown as being housed within housing 302. As can beappreciated by the illustration shown in FIG. 14C, central axis 1309 candivide receiving element 1300 in two halves: a first half 1410 and asecond half 1412. First half 1410 positioned closest to transmittingelement 200 can have a cross section that is substantially similar toreceiving element 400 in FIGS. 4 and 5. Thus, the electricalinteractions during wireless power transfer are substantially similar.For instance, during wireless power transfer, coil 202 can generate aplethora of time-varying magnetic flux 1402, a substantial portion ofwhich can be redirected by ferromagnetic structure 204 so that the fluxexits or enters through interfacing surfaces 208 and 206 and enters orexits ferromagnetic structure 1304 through interfacing surfaces 1306 and1308. Thus, a concentration of magnetic flux 1402 can exist in regions1404 between corresponding interfacing surfaces/rings of ferromagneticstructures 204 and 1304. In some embodiments, surfaces of interfacingsurfaces 1306 and 1308 are parallel to central axis 1309.

Furthermore, depending on the direction of current flowing through coil202, a substantial amount of magnetic flux 1402 generated by coil 202can first flow out of interfacing surface 208 and into interfacingsurface 1308 of ferromagnetic structure 1304, which can then propagatethrough ferromagnetic structure 1304 and exit out of interfacing surface1306 so that magnetic flux 1402 can enter back into ferromagneticstructure 204 through interfacing surface 206. The resulting flowmagnetic flux forms a magnetic loop 1406 that induces a current in coil1302 that can be used to provide power to an accessory device withinwhich receiving element 1300 is disposed. Although magnetic loop 1406 isshown in a clockwise direction, magnetic loop 1406 can also propagate ina counter-clockwise direction when current is flowing through coil 202in an opposite direction. It is to be appreciated that because receivingelement 1300 is symmetrical around central axis 1309, second half 1412can be identical to first half 1410 but just arranged in a mirror imageof first half 1410. Thus, if receiving element 1300 is rotated roundcentral axis 1309, the half closest to transmitting element 200 will beidentical to first half 1410 as shown in FIG. 14C and have the sameelectrical interactions. As such, receiving element 1300 can receivepower regardless of how it is rotated around central axis 1309, therebysubstantially increasing the ease at which receiving element 1300 canreceive power from transmitting element 200.

Although FIG. 14C illustrates transmitting element 200 as transmittingpower to receiving element 1300, embodiments are not so limited. Otherembodiments can reverse the transfer of power such that transmittingelement 200 receives power from receiving element 1300. As an example,current can be driven into coil 1302 of receiving element 1300 such thatcoil 1302 generates time-varying magnetic flux. The generatedtime-varying magnetic flux can be redirected by ferromagnetic structure1304, which can be received by ferromagnetic structure 1304. Thereceived magnetic flux in ferromagnetic structure 1304 can induce acorresponding current in coil 1302, which can be used to provide powerto a host device within which transmitting element 200 is disposed.

III. Alignment Devices for Inductive Interconnection Systems

As can be understood by the disclosures herein, efficient power transferis achieved when a receiving element in an accessory device is alignedwith a transmitting element in a host device. To achieve alignmentbetween the two elements, one or more alignment devices can beimplemented. However, when the receiving element is substantiallysymmetrical about its central axis, e.g., receiving element 1300 in FIG.13A, and housed within a housing of an accessory device that is alsosubstantially symmetrical about its central axis, e.g., a stylus, smartpencil, and the like, then the alignment device for the accessory devicemay also need to be able to align the receiving element with thetransmitting element in any degree of angular rotation. According tosome embodiments of the present disclosure, one or more alignmentdevices can be implemented in the host device and the accessory deviceto enable the accessory device to align with the host device at anypoint along a complete 360° range of angular rotation.

FIG. 15 is a simplified illustration of an exemplary host alignmentdevice 1500 for a host device having a single center magnet 1502,according to some embodiments of the present disclosure. Host alignmentdevice 1500 can be housed within the host device to align an accessorydevice to the host device by aligning to an accessory alignment devicein the accessory device. Center magnet 1502 can be any suitablepermanent magnet, such as a neodymium magnet. Host alignment device 1500can have an interfacing surface 1504 that is directed toward theaccessory alignment device to attract the accessory alignment device, aswill be discussed further herein. In some embodiments, center magnet1502 can be arranged such that its magnetic poles are positionedvertically, meaning that its north and south pole are positioned along avertical axis. For instance, as shown in FIG. 15, center magnet 1502 canhave a north pole positioned at interfacing surface 1504 so thatmagnetic flux 1505 is directed outward to attract an accessory alignmentdevice that has a corresponding south pole.

According to some embodiments, center magnet 1502 can be positionedbetween two ferromagnetic structures 1506 and 1508. Ferromagneticstructures 1506 and 1508 are not permanent magnets, but are structuresformed of ferromagnetic material through which magnetic flux is allowedto propagate. As an example, ferromagnetic structures 1506 and 1508 canbe formed of ferritic stainless steel, iron, nickel, cobalt, or anyother suitable material. In some embodiments, ferromagnetic structures1506 and 1508 have widths 1510 and 1512 that are larger than a width1514 of center magnet 1502. Having wider ferromagnetic structures 1506and 1508 can allow magnetic flux to propagate farther away from centermagnet 1502 so that magnetic flux is not concentrated in regionsimmediately beside center magnet 1502, thereby smoothing the forceprofile as an accessory alignment device is moved in that region, aswill be discussed further herein with respect to FIGS. 18-19.

With further reference to FIG. 15, host alignment device 1500 can alsoinclude chamfered regions 1516 and 1518 positioned at the interfaces ofcenter magnet 1502 and both ferromagnetic structures 1506 and 1508. Insome embodiments, chamfered regions 1516 and 1518 are sloped surfacesthat form a V-shape where the lowest end of the sloped surfaces arepositioned at the interface between center magnet 1502 and bothferromagnetic structures 1506 and 1508. Chamfered regions 1516 and 1518can enlarge the separation distance between the top corners of centermagnet 1502 and both ferromagnetic structures 1506 and 1508 to decreasethe strength of the magnetic flux at chamfered regions 1516 and 1518 aswell as minimize magnetic flux leakage due to a high concentration ofmagnetic flux that would exist at those regions if no chamferingexisted. By decreasing the magnetic flux strength of chamfered regions1516 and 1518, the force profile exerted on an accessory alignmentdevice as it moves into alignment with host alignment device 1500 can besmoothed, as will be discussed further herein. Furthermore, byminimizing magnetic flux leakage at chamfered regions 1516 and 1518,magnetically sensitive devices can be brought close to host alignmentdevice 1500 without suffering from a negative interaction. For instance,minimizing magnetic flux leakage can prevent a credit card from beingdemagnetized when it is inadvertently brought close to host alignmentdevice 1500.

In some embodiments, host alignment device 1500 can include outerchamfered edges 1520 and 1522 for further smoothing the force profileexerted on an accessory alignment device. For instance, outer chamferededges 1520 and 1522 can slope downwards away from center magnet 1502 sothat as an accessory alignment device moves toward center magnet 1502,the attractive force on the accessory alignment device gradually buildsup. If outer chamfered edges 1520 and 1522 did not exist, then magneticflux propagating out of ferromagnetic structures 1506 and 1508 maydramatically begin attracting the accessory alignment device as it movesclose to ferromagnetic structures 1506 and 1508. According to someembodiments of the present disclosure, one or more strengthening magnetscan be implemented in a host alignment device to enhance the strength ofmagnetic attraction with an accessory alignment device, as discussedherein with respect to FIG. 16.

FIG. 16 is a simplified illustration of an exemplary host alignmentdevice 1600 for a host device having a center magnet 1602 and twostrengthening magnets 1604 and 1606, according to some embodiments ofthe present disclosure. Host alignment device 1500 can be housed withinthe host device to align an accessory device to the host device byaligning to an accessory alignment device in the accessory device.Alignment device 1600 can have an interfacing surface 1608 that isdirected toward the accessory alignment device to attract the accessoryalignment device, as will be discussed further herein. Similar to centermagnet 1502, center magnet 1602 can be arranged such that its magneticpoles are positioned vertically, meaning that its north and south polesare positioned along a vertical axis. For instance, as shown in FIG. 16,center magnet 1602 can have a north pole positioned at interfacingsurface 1608 so that magnetic flux 1605 is directed outward to attractan accessory alignment device that has a corresponding south pole.

However, unlike host alignment device 1500, host alignment device 1600can include two strengthening magnets 1604 and 1606 on opposite sides ofcenter magnet 1602. Strengthening magnets 1604 and 1606 can be arrangedsuch that their magnetic poles are positioned along a horizontal axis.Further, the orientation of the magnetic poles of strengthening magnets1604 and 1606 can be arranged such that their magnetic flux aggregatesand strengthens the magnetic flux generated by center magnet 1602. Forinstance, if center magnet is arranged such that its north pole isupwards and its south pole is downwards, strengthening magnet 1604 isarranged such that its north pole is on the right and its south pole ison the left, and strengthening magnet 1606 is arranged such that itsnorth pole is on the left and its south pole is on the right.Accordingly, magnetic flux from strengthening magnets 1604 and 1606 canfirst propagate toward center magnet 1602 and then aggregate withmagnetic flux generated by center magnet 1602 to provide a strengthenedmagnetic flux 1605 propagating upward toward an accessory alignmentdevice. In some embodiments, strengthening magnets 1604 and 1606 havepolarities that are opposite from each other so that magnetic flux fromboth magnets are either directed toward center magnet 1602 or away fromcenter magnet 1602. Accordingly, the poles of strengthening magnets thatare positioned beside center magnet 1602 can be the same pole as thepole of center magnet 1602 that is oriented upward in the direction ofan accessory alignment device.

According to some embodiments, center magnet 1602 and strengtheningmagnets 1604 and 1606 are positioned between two ferromagneticstructures 1607 and 1609. For instance, strengthening magnet 1604 can bepositioned between ferromagnetic structure 1607 and center magnet 1602,and strengthening magnet 1606 can be positioned between ferromagneticstructure 1609 and center magnet 1602. Ferromagnetic structures 1607 and1609 can be substantially similar to ferromagnetic structures 1506 and1508 in FIG. 15 in form and function. Thus, ferromagnetic structures1607 and 1609 are structures formed of ferromagnetic material throughwhich magnetic flux is allowed to propagate, and have widths 161160 and1612 that are larger than a width 1614 of center magnet 1602. Havingwider ferromagnetic structures 1607 and 1609 can allow magnetic flux topropagate farther away from strengthening magnets 1604 and 1606 so thatmagnetic flux is not concentrated in regions immediately besidestrengthening magnets 1604 and 1606, thereby smoothing the force profileas an accessory alignment device is moved in that region, as will bediscussed further herein with respect to FIGS. 18-19.

With further reference to FIG. 16, host alignment device 1600 can alsoinclude chamfered regions 1616 and 1618 positioned at the interfaces ofcenter magnet 1502 and both strengthening magnets 1604 and 1606. Similarto chamfered regions 1516 and 1518, chamfered regions 1616 and 1618 candecrease the strength of the magnetic flux at chamfered regions 1616 and1618 as well as minimize magnetic flux leakage due to a highconcentration of magnetic flux that would exist at those regions if nochamfering existed. Thus, the force profile exerted on an accessoryalignment device as it moves into alignment with host alignment device1500 can be smoothed, as will be discussed further herein. And,magnetically sensitive devices can be brought close to host alignmentdevice 1600 without suffering from a negative interaction, as discussedherein with respect to FIG. 15.

FIGS. 15 and 16 illustrate center magnets 1502 and 1602 has having anorth pole oriented upward and a south pole oriented downward; however,it is to be appreciated that embodiments are not limited to suchconfigurations. Some embodiments can have center magnets 1502 and 1602arranged in opposite polarities. In such instances, strengtheningmagnets 1604 and 1606 can also be arranged in opposite polarities.

Although host alignment device 1600 is not shown as having outerchamfered edges, like outer chamfered edges 1520 and 1522 in FIG. 15, itis to be appreciated that host alignment device 1600 can include outerchamfered edges in some embodiments for further smoothing the forceprofile exerted on an accessory alignment device.

According to some embodiments of the present disclosure, an accessoryalignment device can be configured to be attracted to the center magnetof a host alignment device at any point along a complete 360° angularrotation. FIG. 17A illustrates an exemplary accessory alignment device1700 that can be attracted to a host alignment device at any point alonga complete 360° angular rotation, according to some embodiments of thepresent disclosure. Accessory alignment device 1700 can include a pairof magnets 1702 and 1704 positioned between a center ferromagneticstructure 1706 and two side ferromagnetic structures 1028 and 1710. Forinstance, magnet 1702 can be positioned between center ferromagneticstructure 1706 and side ferromagnetic structure 1708, and magnet 1704can be positioned between center ferromagnetic structure 1706 and sideferromagnetic structure 1710. Magnets 1702 and 1704 can be any suitablepermanent magnets, e.g., neodymium magnets, and ferromagnetic structures1706, 1708, and 1710 can be formed of any suitable ferromagneticmaterial, e.g., ferritic stainless steel, iron, nickel, cobalt, or anyother suitable material.

Magnetic poles of magnets 1702 and 1704 can be arranged horizontally andoriented such that both of their magnetic flux propagate toward or awayfrom center ferromagnetic structure 1706. Accordingly, their magneticflux can aggregate and strengthen in center ferromagnetic structure 1706and then propagate outward in all radial directions 1714 away from (ortowards depending on polarity) its central axis 1712. For instance,magnets 1702 and 1704 can have their south poles oriented toward centerferromagnetic structure 1706 such that magnetic flux propagates towardcentral axis 1712 from all radial directions 1714. In some embodiments,accessory alignment device 1700 has a substantially cylindrical shape sothat its structure is axially symmetrical with respect to central axis1712. Thus, accessory alignment device 1700 can be attracted to anymagnet having a north pole in any degree of rotation around its centralaxis 1712, as better shown in FIG. 17B.

FIG. 17B illustrates an exemplary perspective view of an alignmentsystem 1701 including an accessory alignment device (e.g., accessoryalignment device 1700) and a host alignment device (e.g., host alignmentdevice 1600), according to some embodiments of the present disclosure.As shown in FIG. 17B, accessory alignment device 1700 is being attractedto host alignment device 1600. When accessory alignment device 1700 isbrought close to host alignment device 1600, forces generated bycomplementary magnetic fluxes draw them toward alignment. For ease ofunderstanding, the magnetic polarities discussed herein with respect toFIGS. 16 and 17A are also applied to FIG. 17B. During alignment, hostalignment device 1600 has a strong north polarity at its interfacingsurface 1608 that attracts the south polarity of center ferromagneticstructure 1706 of accessory alignment device 1700. The substantiallyaxially symmetrical structure of accessory alignment device 1700 enablesit to be attracted to host alignment device 1600 in any degree ofrotation 1716 around its central axis 1712. In some embodiments, achannel 1711 can be positioned along central axis 1712 and providevacant space through which objects, such as wires, cables, and the like,can tunnel.

As mentioned herein, accessory alignment device 1700 further includesside ferromagnetic structures 1708 and 1710. Side ferromagneticstructures 1708 and 1710 can help spread out the propagation of magneticflux so that there is not a high concentration of magnetic flux at theinterface between magnets 1702 and 1704. The spreading of magnetic fluxby ferromagnetic structures 1708, 1710, 1607, and 1609 in conjunctionwith the chamfered edges 1616 and 1618 helps smooth the force profile ofan attraction force between devices 1700 and 1600 such that the userfeels a smooth attraction between them.

FIGS. 18 and 19 are graphs illustrating exemplary force profiles betweenaccessory and host alignment devices. Specifically, FIG. 18 is a graphillustrating a force profile 1802 between accessory and host alignmentdevices without chamfered edges (e.g., chamfered edges 1616 and 1618 inFIG. 17B), and FIG. 19 is a graph illustrating a force profile 1902between accessory and host alignment devices with chamfered edges,according to some embodiments of the present disclosure. Both graphshave an x-axis representing a distance between the center of anaccessory alignment device and the center of a host alignment devicewhere 0 represents alignment. Both graphs also have a y-axisrepresenting a degree of force where positive values indicate arepelling force and negative values indicate an attractive force.

As shown in FIG. 18, without the chamfered edges, force profile 1802 caninclude peaks 1804 and 1806 of high repelling forces experienced by auser. These peaks can be positioned at the interfaces between a centermagnet (e.g., 1602 in FIGS. 16 and 17B) and both strengthening magnets(e.g., 1604 and 1606 in FIGS. 16 and 17B). Thus, the user will feelstrong resistance as accessory alignment device 1700 moves toward thealigned position before feeling a strong attractive force as the twodevices are aligned. In contrast, force profile 1902 as shown in FIG. 19does not have peaks 1804 and 1806 but instead has flat regions 1904 and1906 where the peaks would be if the host alignment device did not havechamfered edges. The chamfered edges reduce the concentration ofmagnetic flux at that area so a strong repelling force does not exist torepel the accessory alignment device at those locations. As a result ofhaving chamfered regions, the force profile is substantially smoother,thereby resulting a better user feel.

FIG. 20 illustrates an exemplary wireless charging system where a hostdevice 2000 is aligned with an exemplary accessory device 2002configured to receive charge at any point along a complete 360° angularrotation, and/or an exemplary accessory device 2003 whose housingincludes a flat portion that makes contact with host device 2000,according to some embodiments of the present disclosure. Host device2000 can include host alignment devices 2004-2007 and transmittingelements 2008-2009. Each host alignment device 2004-2007 can beconfigured as host alignment device 1600 discussed herein with respectto FIG. 16. Further, each transmitting element 2008-2009 can beconfigured as transmitting element 200 discussed herein with respect toFIG. 2A. Host alignment devices 2004-2007 and transmitting elements2008-2009 can be housed within housing 2001 of host device 2000.

As further shown in FIG. 20, accessory device 2002 can include accessoryalignment devices 2010-2011 and receiving element 2012. Each accessoryalignment device 2010-2011 can be configured as accessory alignmentdevice 1700 discussed herein with respect to FIG. 17A. Further,receiving element 2012 can be configured as receiving element 1300discussed herein with respect to FIG. 13A. Accessory alignment devices2010-2011 and receiving element 2020 can be housed within housing 2013of accessory device 2002. According to some embodiments of the presentdisclosure, housing 2013 can be axially symmetrical with respect to acentral axis 2014 (e.g., substantially cylindrical), and able to receivepower from host device 2000 by having its receiving element 2012interact with time-varying magnetic flux generated by transmittingelement 2009. Accessory device 2002 can achieve alignment with hostdevice 2000 to receive power by having its accessory alignment devices2010 and 2011 interact with respective host alignment devices 2005 and2007. By being able to align with and receive power from host device2000 in any degree of angular rotation around central axis 2014, theease at which accessory device 2002 receives power is substantiallyimproved.

Host device 2000 can additionally or alternatively be configured towirelessly charge accessory device 2003. Accessory device 2003 can be anaccessory device that includes a receiving element 2020 that can receivecharge when it is positioned across from a transmitting element asdiscussed herein with respect to FIGS. 5 and 8A-8B. Thus, receivingelement 2020 can be configured as receiving element 400 in FIG. 4 andreceiving element 612 in FIGS. 6, 7A-7B, 8A-8B, and 9. In suchembodiments, accessory device 2003 can include a housing that has a flatportion that makes contact with host device 2000 to enable wirelesspower transfer, as discussed herein with respect to FIGS. 6, 7A-7B, and8A-8B. In addition to receiving element 2020, accessory device 2003 canalso include accessory alignment devices 2022 and 2024. Becauseaccessory device 2003 may not be able to receive charge at any pointalong a complete 360° angular rotation, alignment devices 2022 and 2024may not need to be configured to be cylindrical, such as alignmentdevices 2010 and 2011. Instead, accessory alignment devices 2022 and2024 can be substantially rectangular and can be positioned against oneside of accessory device 2003 instead of having to extend around theentire housing, as is necessary for alignment devices 2010 and 2011.Accessory alignment devices 2022 and 2024, however, can still beconfigured to have the same magnetic structure as alignment devices 2010and 2011, meaning accessory alignment devices 2022 and 2024 can includea pair of magnets positioned between a center ferromagnetic structureand two side ferromagnetic structures, as discussed herein with respectto FIGS. 17A-17B for magnetically attracting to, and aligning with,respective host alignment devices 2004 and 2006.

Host device 2000 can be any suitable portable electronic device havingat least one of a computing system, communication system, sensor system,memory bank, user interface system, battery, and power transmittingcircuitry, such as host device 101 discussed herein with respect toFIG. 1. In some embodiments, host device 2000 is a tablet computer,laptop computer, smart phone, or any other suitable device.Additionally, accessory device 2002 can be any suitable electronicdevice having an operating system, power receiving circuitry, and abattery, such as accessory device 103 in FIG. 1. Accessory device 2002can be operated to input data into host device 2000. As an example,accessory device 2002 can be a stylus or a smart pencil that a user canuse to make contact with host device 101 to input data into host device101. Accordingly, in some embodiments, accessory device 2002 can includean interfacing end 2016 that is configured to make contact with housing2001 of host device 2000. For instance, interfacing end 2016 can have astructure that tapers to a tip to mimic the tip of a conventionalwriting utensil, such as a pencil or pen.

Although FIG. 20 illustrates host device 2000 as having four hostalignment devices 2004-2007 and two transmitting elements 2008-2009,embodiment are not so limited. Other embodiments can have more or lesshost alignment devices and transmitting elements. Furthermore,embodiments are not limited to configurations where host alignmentdevices 2004-2007 and transmitting elements 2008-2009 are positionedeither side of host device 2000. It is to be appreciated that hostalignment devices 2004-2007 and transmitting elements 2008-2009 can bepositioned in any suitable location that enables power transfer withaccessory device 2002, such as a top and/or bottom edges of host device2000.

In addition to the embodiments discussed above, the followingembodiments are also envisioned herein. In particular embodiments, areceiving element can include a ferromagnetic structure axiallysymmetrical around a central axis disposed along a length of theferromagnetic structure. The ferromagnetic structure can include agroove region defining two end regions on opposing sides of the grooveregion, where the groove region has a smaller length than the two endregions. The receiving element can also include an inductor coil woundabout the groove region of the ferromagnetic structure and in betweenthe two end regions.

The receiving element, in some cases, can further include a channeldisposed along the central axis. The ferromagnetic structure can be inthe shape of a cylinder. The end regions can be configured to directpropagation of magnetic flux toward a transmitting element. In someembodiments, the ferromagnetic structure further includes sidewalls thatextend a distance equal to or greater than a thickness of the inductorcoil. The sidewalls can be positioned between the groove region and thetwo end regions.

In additional embodiments, an inductive interconnection system includesa transmitting element and a receiving element. The transmitting elementcan include a transmitting ferromagnetic structure having a transmittinggroove region defining two transmitting end regions disposed on opposingsides of the transmitting groove region, where the transmitting grooveregion has a smaller length than the two transmitting end regions. Thetransmitting element can also include a transmitting inductor coil woundabout the transmitting groove region of the transmitting ferromagneticstructure and in between the two transmitting end regions. Thetransmitting inductor coil can be configured to generate time-varyingmagnetic flux through the transmitting ferromagnetic structure. Thereceiving element can include a receiving ferromagnetic structureaxially symmetrical around a central axis disposed along a length of thereceiving ferromagnetic structure. The receiving ferromagnetic structurecan include a receiving groove region defining two receiving end regionson opposing sides of the receiving groove region, where the receivinggroove region has a smaller length than the two receiving end regions.The receiving element can also include a receiving inductor coil woundabout the receiving groove region of the receiving ferromagneticstructure and in between the two receiving end regions. The receivinginductor coil can be configured to receive a current induced by thetime-varying magnetic flux.

The transmitting end regions can each include respective transmittinginterfacing surfaces that face toward the receiving element, where thereceiving end regions each include respective receiving interfacingsurfaces that face toward the transmitting element. The transmittinginterfacing surfaces can face toward at least a portion of the receivinginterfacing surfaces. The receiving interfacing surfaces can be axiallysymmetrical around the central axis. The receiving ferromagneticstructure can further include a channel disposed along the central axis.The receiving ferromagnetic structure can be in the shape of a cylinder.

In some further embodiments, a stylus for inputting data into a hostdevice can include a cylindrical housing, power receiving circuitrydisposed within the cylindrical housing, a receiving element disposedwithin the cylindrical housing and coupled to the power receivingcircuitry, and an operating system coupled to the power receivingcircuitry and the receiving element, and configured to operate the powerreceiving circuitry and the receiving element to receive power from thehost device. The receiving element can include a ferromagnetic structureaxially symmetrical around a central axis disposed along a length of theferromagnetic structure, the ferromagnetic structure comprising a grooveregion defining two end regions on opposing sides of the groove region,where the groove region has a smaller length than the two end regions,and an inductor coil wound about the groove region of the ferromagneticstructure and in between the two end regions.

The ferromagnetic structure can further include a channel disposed alongthe central axis. The ferromagnetic structure can be in the shape of acylinder. The end regions can be configured to direct propagation ofmagnetic flux toward a transmitting element. The ferromagnetic structurecan further include sidewalls that extend a distance equal to or greaterthan a thickness of the inductor coil. The sidewalls can be positionedbetween the groove region and the two end regions. The stylus canfurther include an interfacing end that is configured to make contactwith the host device to input data into the host device. The interfacingend can have a structure that tapers to a tip.

In some embodiments, an alignment device includes a center magnet havingpoles arranged in a vertical orientation, first and second strengtheningmagnets disposed on opposite ends of the center magnet, the first andsecond strengthening magnets having poles arranged in a horizontalorientation, and first and second ferromagnetic structures disposed onouter ends of corresponding first and second strengthening magnets suchthat the first strengthening magnet is disposed between the firstferromagnetic structure and the center magnet, and the secondstrengthening magnet is disposed between the second ferromagneticstructure and the center magnet.

The first and second strengthening magnets can be opposite in polarity.The first and second ferromagnetic structures can each have a firstwidth and the center magnet can have a second width less than the firstwidth. The alignment device can further include chamfered regionsdisposed at interfaces between the center magnet and the first andsecond strengthening magnets. The chamfered regions can be formed ofsloped surfaces in V-shapes where lowest ends of the sloped surfaces arepositioned at interfaces between the center magnet and the first andsecond strengthening magnets. The alignment device can further includeouter chamfered edges positioned at outer ends of the alignment devicefarthest away from the center magnet, where the outer chamfered edgesare formed of sloped surfaces sloping downwards away from the centermagnet. In some instances, the center magnet can include an interfacingsurface having a first polarity, the first strengthening magnet having asecond polarity oriented towards the right side, and the secondstrengthening magnet having a third polarity oriented towards the leftside, where the first, second, and third polarities are the samepolarity.

In some additional embodiments, an alignment device includes a centerferromagnetic structure; first and second magnets disposed on oppositeends of the center ferromagnetic structure, the first and second magnetshaving polar ends that are arranged in a horizontal orientation; andfirst and second side ferromagnetic structures disposed on ends of thefirst and second magnets such that the first magnet is disposed betweenthe first side ferromagnetic structure and the center ferromagneticstructure, and the second magnet is disposed between the second sideferromagnetic structure and the center ferromagnetic structure.

The first and second magnets can be opposite in polarity. The alignmentdevice can be axially symmetrical around a central axis disposed along alength of the alignment device. The alignment device can further includea channel disposed along the central axis. The alignment device can besubstantially cylindrical.

In some further embodiments, a portable electronic device includes ahousing, a battery disposed within the housing, a display disposedwithin the housing and configured to perform user interface functions, aprocessor disposed within the housing and coupled to the display andconfigured to command the display to perform the user interfacefunctions, a transmitting element disposed within the housing, and powertransmitting circuitry coupled to the processor and the battery, wherethe power transmitting circuitry is configured to route power from thebattery to the transmitting element. The transmitting element caninclude a center magnet having poles arranged in a vertical orientation,first and second strengthening magnets disposed on opposite ends of thecenter magnet, the first and second strengthening magnets having polesarranged in a horizontal orientation; and first and second ferromagneticstructures disposed on outer ends of corresponding first and secondstrengthening magnets such that the first strengthening magnet isdisposed between the first ferromagnetic structure and the centermagnet, and the second strengthening magnet is disposed between thesecond ferromagnetic structure and the center magnet.

The first and second strengthening magnets can be opposite in polarity.The first and second ferromagnetic structures can each have a firstwidth and the center magnet can have a second width less than the firstwidth. The transmitting element can further include chamfered regionsdisposed at interfaces between the center magnet and the first andsecond strengthening magnets. The chamfered regions can be formed ofsloped surfaces in V-shapes where lowest ends of the sloped surfaces arepositioned at interfaces between the center magnet and the first andsecond strengthening magnets. The transmitting element can furtherinclude outer chamfered edges positioned at outer ends of the alignmentdevice farthest away from the center magnet, where the outer chamferededges are formed of sloped surfaces sloping downwards away from thecenter magnet. In some cases, the center magnet can include aninterfacing surface having a first polarity, the first strengtheningmagnet can have a second polarity oriented towards the right side, andthe second strengthening magnet can have a third polarity orientedtowards the left side, where the first, second, and third polarities arethe same polarity. The portable electronic device can be a tablet.

Although the invention has been described with respect to specificembodiments, it will be appreciated that the invention is intended tocover all modifications and equivalents within the scope of thefollowing claims.

What is claimed is:
 1. A receiving element, comprising: a ferromagneticstructure axially symmetrical around a central axis disposed along alength of the ferromagnetic structure, the ferromagnetic structurecomprising a groove region defining two end regions on opposing sides ofthe groove region, wherein the groove region has a smaller length thanthe two end regions; and an inductor coil wound about the groove regionof the ferromagnetic structure and in between the two end regions. 2.The receiving element of claim 1, further comprising a channel disposedalong the central axis.
 3. The receiving element of claim 1, wherein theferromagnetic structure is in the shape of a cylinder.
 4. The receivingelement of claim 1, wherein the end regions are configured to directpropagation of magnetic flux toward a transmitting element.
 5. Thereceiving element of claim 1, wherein the ferromagnetic structurefurther comprises sidewalls that extend a distance equal to or greaterthan a thickness of the inductor coil.
 6. The receiving element of claim5, wherein the sidewalls are positioned between the groove region andthe two end regions.
 7. An inductive interconnection system, comprising:a transmitting element comprising: a transmitting ferromagneticstructure having a transmitting groove region defining two transmittingend regions disposed on opposing sides of the transmitting grooveregion, wherein the transmitting groove region has a smaller length thanthe two transmitting end regions; and a transmitting inductor coil woundabout the transmitting groove region of the transmitting ferromagneticstructure and in between the two transmitting end regions, thetransmitting inductor coil configured to generate time-varying magneticflux through the transmitting ferromagnetic structure; and a receivingelement, comprising: a receiving ferromagnetic structure axiallysymmetrical around a central axis disposed along a length of thereceiving ferromagnetic structure, the receiving ferromagnetic structurecomprising a receiving groove region defining two receiving end regionson opposing sides of the receiving groove region, wherein the receivinggroove region has a smaller length than the two receiving end regions;and a receiving inductor coil wound about the receiving groove region ofthe receiving ferromagnetic structure and in between the two receivingend regions, the receiving inductor coil configured to receive a currentinduced by the time-varying magnetic flux.
 8. The inductiveinterconnection system of claim 7, wherein the transmitting end regionseach include respective transmitting interfacing surfaces that facetoward the receiving element, and wherein the receiving end regions eachinclude respective receiving interfacing surfaces that face toward thetransmitting element.
 9. The inductive interconnection system of claim8, wherein the transmitting interfacing surfaces face toward at least aportion of the receiving interfacing surfaces.
 10. The inductiveinterconnection system of claim 8, wherein the receiving interfacingsurfaces are axially symmetrical around the central axis.
 11. Theinductive interconnection system of claim 7, further comprising achannel disposed along the central axis.
 12. The inductiveinterconnection system of claim 7, wherein the receiving ferromagneticstructure is in the shape of a cylinder.
 13. A stylus for inputting datainto a host device, the stylus comprising: a cylindrical housing; powerreceiving circuitry disposed within the cylindrical housing; a receivingelement disposed within the cylindrical housing and coupled to the powerreceiving circuitry, the receiving element comprising: a ferromagneticstructure axially symmetrical around a central axis disposed along alength of the ferromagnetic structure, the ferromagnetic structurecomprising a groove region defining two end regions on opposing sides ofthe groove region, wherein the groove region has a smaller length thanthe two end regions; and an inductor coil wound about the groove regionof the ferromagnetic structure and in between the two end regions; andan operating system coupled to the power receiving circuitry and thereceiving element, and configured to operate the power receivingcircuitry and the receiving element to receive power from the hostdevice.
 14. The stylus of claim 13, further comprising a channeldisposed along the central axis.
 15. The stylus of claim 13, wherein theferromagnetic structure is in the shape of a cylinder.
 16. The stylus ofclaim 13, wherein the end regions are configured to direct propagationof magnetic flux toward a transmitting element.
 17. The stylus of claim13, wherein the ferromagnetic structure further comprises sidewalls thatextend a distance equal to or greater than a thickness of the inductorcoil.
 18. The stylus of claim 17, wherein the sidewalls are positionedbetween the groove region and the two end regions.
 19. The stylus ofclaim 13, further comprising an interfacing end that is configured tomake contact with the host device to input data into the host device.20. The stylus of claim 19, wherein the interfacing end has a structurethat tapers to a tip.